Windsor (England)

If you go to London, a day-trip to Windsor is clearly a must.  It's a cute small town again.  There you can find the Windsor Castle, home of the Queen.  Its a pretty cool place to see, especially if you get a glance of the Queen.  Like Versailles, it's worth sticking around the village and checking it out.  Not that much to do, but it is very cozy compared to London.